Hole forming tool



Oct. 24, 1939.

w. o. REESER HOLE FORMING TOOL Filed Feb. 19, 1938 A? a l6 A ORA r 1 tive has been by laboriously filing the hole to the ture by first making a small hole, less than the desired increased diameter. A tubular punch as desired diameter, and then completing the restruck by a hammer cannot be used for lack of moval of the remaining metal by the application suitable backing, and furthermore, it is difficult of the tool I have invented, as hereinafter deto obtain a clean, smooth hole, if the metal is of scribed.

such gauge or thickness as to require. more than A further object of my invention is to provide 20 use of my tool in 'this type of work often this phenomenon exhibited by such a metal as 5 a tool useful for making holes in sheet metal ment of the material by the walls of the punch 30 555 junction or outlet boxes, and must be filed off. ment of my tool; '55

Patented Oct. 24, 1939 UNITED STATES sATENr HOLE FORMING TOOL William 0. Reeser, Dayton, Ohio Application February 19, 1938, Serial No. 191,467 5 Claims. (01. 164-401) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manu- Besides being a source of dangerous injury to the factured and used by or for the Government for fingers of workmen, the burr prevents tightening governmental purposes, without the payment to of the lock nut on the conduit to a flush rigid fit me of any royalty thereon. with the side walls of the box. Since this lock My invention relates generally to tools for sheet nut often may be used to protect the contents of metal work, or other sheet material, and particuthe box from the elements, or to provide an eleclarly to tools for cutting and enlarging holes in trical contact for ground in some systems, it is such sheets. essential that this nut should fit tightly against A particular use is found in electrical com the box. In the case of electrical boxes in air- Hl struction'work for the enlarging or knock-out craft, where aluminum fittings and nipples are 10 holes in electrical junction or outlet boxes to reused, the rough edge on the hole of a box, in coceive a larger size of conduit than provided for operation with a loose connection, will wear or cut by the original knock-out in the box. Heretothrough the aluminum fitting. I have succeeded fore, the usual way of accomplishing this objecin making holes without this objectionable feaone blow of the hammer. A still further problem a tool for making holes in soft metals, such as is that, in many instances, there is insufficient aluminum, which exhibit a tendency to become space for the use of striking means, such as a distorted or grow at the periphery as a rehammer, or for the use of boring means. The action to the application of impact. Because of eliminates the necessity for removing and replacaluminum, it is difficult to make a hole in a sheet ing junction boxes in confined places, thereby of small dimensions by the use of a tubular punch saving much cost of labor and materials. It is struck by a hammer without distortion of the therefore an object of my invention to provide periphery of the sheet due to the lateral displacein places and under conditions inaccessible to Where it is necessary that the periphery be kept large and bulky tools, and where there is insufiiin its original alignment or dimensions, or in the cient space for the use of striking means, such case of electrical junction boxes, the expanded as a hammer. portion must be removed by filing or grinding.

Although my invention is defined as a tool for Since the cutting action of my tool is accomcutting or enlarging holes in sheet metal, its plished gradually and without impact, this primary object is to accomplish a hole of given phenomenon of growth is avoided, and no diameter with a clean, burrless cut, and it is only remedial action is needed. incidental to this object, that it is necessary to A still further object of my invention is to 40 make a smaller hole by any ordinary means beprovide in a tool of this character a punch die 40 e the application of y 13001 accomplishing capable of self-centering in a hole to be enlarged the hole of desired diameter. In the case of holes by Said 1 1 in electrical boxes, the smaller hole is obtained The above and Still furth r Objects and by striking out the knockout portmn" if this vantages of the invention will become apparent gggfgg g 2 3222 222 g3 from a study of the following specification taken 45 ist bore or punch a smaller hole than the in t i with the accompanymg drawing "knockout" at the desired center. Heretofore, wherein like reference characters designatecorthe instruments or tools used to make holes of a respondms parts throughout the Several mews given diameter, such as drills, punches, or dies, and Wherem: 50

have left t l b r Or rough edge, on the fa Fig. 1 is a vertical section through one embodiside of the sheet metal. This rough edge left, on ment of my tool, assembled with the metal blank holes is particularly objectionable inthe case of in position to be out;

enlarging the knock-out holes of the electrical Fig. 2 is an exploded view of the same embodi- Fig. 3 is a View similar to Fig. 1 showing another embodiment of my tool;

Fig. 4 is a bottom plan View of Fig. 3; Fig. 5 is a fragmentary View partially in section 5 similar to Fig. 1 showing another embodiment of my invention;

Fig. 6 is a side elevation view of one form oi cutting die employed in my invention;

Fig. 7 is a bottom plan view of the same die;

Fig. 8 is a perspective view of one form of die used in my invention;

Figs. 9, l0, and 11 are section views showing progressive stages in the cutting of a metal blank as accomplished by my invention.

Fig. 12 is a fragmentary section View showing a further arrangement of the cutting dies.

Now referring to the drawing in detail, it will be seen from Figs. 1 and 2 that my tool consists of a driving screw member I; having at one end threadedly mounted thereon an annular support or carrier 2; a washer 3 carried on the element 2 and loosely mounted on said driving screw; a tubular cutting die 4, provided with a bevelled knife-like cutting edge 5, surrounding said driving screw, mounted on said washer and spaced and centralized with respect to said driving screw by means of an annular spacer or guide 5, said spacer being of a length less than the tubular die 4 in order to provide a recess I in the top portion sheet material; and a cutting die 9 complethereof to receive the slug 8 to be cut from the mentary to the die l, provided with a bore I to receive the driving screw in close fitting and sliding relation, and further provided with a 35 tapered or bevelled portion ii on the end opposite the normal cutting face if. The driving screw is provided with an abutment I3, which limits the travel in one direction of the die 9. This abutment is preferably made an integral part of the driving screw and is in the form of a square-shaped head to enable engagement by a suitable tool for effecting a relative rotation between the driving screw I and the carrier 2, which is also square shaped, to likewise enable engage- 'ment by a proper tool. The shaft of the driving screw should be of sufficient length to permit relative displacement between the cutting members 4 and 9 for receiving therebetween various thicknesses of metal or other materials to be operated on.

It is preferable in the above assembly that the cutting member 9 should have a diameter only a few thousandths less than the inside diameter of the tubular die 4. It is desirable to make the guide 6 as close fitting with the tubular die 4 as practically possible, as it is by means of the guide through its bore I4' cooperating with the driving screw I that the tubular die 1 is kept in alignment with the cutting member 8. The bore H1 in the guide 6, and the bore II) in the cutting member 9 should be as close fitting as possible to the driving screw l in order to assure good alignment. The washer 3 should be of considerably larger diameter than the tubular die 4 in 6 order to serve as a support for dies of various diameters, and its bore I5 should be fairly close fitting to the driving screw I but need not be made with the precision of the bores in the guide or in the cutting member. The washer should be of sufiicient thickness to be rigid for all operations. A few thousandths of an inch clearance is desirable between cutting member 8 and the inside diameter of the tubular die 4 in order to provide for some degree of self-adjustment between the two members when they are being forced together by the advance of the carrier 2 on the driving screw i, upon relative rotation therebetween.

The normal operation of my tool as illustrated in Fig. 1 consists in inserting the driving screw l with the die 9 mounted thereon in the hole I6 in the sheet'material or blank I! to be enlarged to the diameter of the die, said hole having been previously formed in the sheet material or work. The spacing guide 8, tubular die 4, washer 3, and carrier 2 are next mounted on the driving screw on the side of the material opposite the die 9 in the order named. The threaded carrier 2 is then advanced on the threaded portion of the shaft of the driving screw I by relative rotation accomplished by engaging the carrier 2 and the square head of the driving screw by means of suitable tools, thereby urging the tubular die 4 and cutting member 9 towards each other and against the metal blank, shearing from the sheet ma terial the portion 8 of said material or blank under the cutting member 9, as shownin section views, Figs. 9, 10, and 11..

Although the advantages of my tool as a portable hand tool for enlarging and cutting holes in confined or limited areas may be obtained by the use of a flat or right-angled cutting edge on the tubular die 4, or any other conventional type cutting edge in lieu of the bevelled knifelike edge 5, it has been found that this bevelled edge 5, which might also be described as the surface formed by the intersection of a hollow cylinder and a right cone concentric therewith, enables the successful operation in making a hole that is clean cut and free from any burr or rough edge. As a result of this knife-like edge provided on the tubular die 4, the cutting is done in the manner shown in Figs. 9, 10, and 11.

The first application of pressure by means of relative rotation between the carrier 2 and the driving screw I forces the knife-like edge 5 of the tubular die 4 into the metal blank I'I. bevelled edge 5 of the die 4 is driven deeper into the blank, progressively increasing resistance is set up as the area of said die in contact with said metal blank is constantly increasing. Therefore, the tubular die 4 is forced into the metal to a depth where the resistance encountered is equal to the pressure required to shear the entire portion to be cut by the cutting member 9. This position is indicated in Fig. 9. pressure between the dies is now sufficient to force the cutting die 9 into the blank while the die d is maintained in a fairly constant relation to said sheet material, and continued relative rotation of the carrier will complete the shearing of the metal blank, and the portion 8 of the metal blank under the die 9 will be forced into the recess I in the upper end of the die 4. It is to be noted that due to the position of the tubular die 6 imbedded in the metal blank, the final shearing of the metal portion being cut out is accomplished within the plane surfaces of the blank of material as shown in Fig. 11, and that consequently there will be no burr protruding from the metal blank as in the case of ordinary dies, wherein the flat surface of the cutting member 9 would ordinarily cooperate against a rightangled cutting edge on a base die in the position of the tubular die 4. The shearing as 'accomplished by my invention is not only confined to the area on the inside of the hole, but is also complete, since the cutting member 9 is actually drawn within the inside diameter of the tubular As the,

so In Fig. 10, the 7 die 4 as a final process in the cutting. In this respect, it again differsfrom the operation of ordinary dies having right-angled surfaces for cooperating edges, as in a punch press wherein the shearing of the cut-out portion is not completed until the cutting member has reached the opposite side of the metal blank and there is no further cutting action required or possible in cooperation with the base die, but the metal portion is definitely torn from the blank upon. the incipient approach of the cutting member or die to the base die.

There is a further advantage of this type of combined cutting and shearing operation performed by my tool over the straight shearing operation as performed by ordinary dies, in that the original thickness of the blank to be cut is reduced to the extent that the tubular die 4 penetratesinto the blank l1, and, the resulting thickness of metal being less than its original, thickness, the force thereby required to shear said material is accordingly less.

Another novel variation in the use of my tool while being used to enlarge holes is to locate the center of the enlarged hole with respect to the center of the already formed hole. Adapting the principle that a cone will automatically seek the mean center of the hole into which it is inserted, I have provided cutting member 9 with a conical surface on its reverse side, so that, when inverted, it Will engage the sides of the already formed hole while the dies are being aligned. In order for the tool to work in this manner, it is necessary that the diameter of the conical section of said die at its minimum cross section be less than the diameter of the already-formed hole. Having assembled the dies in this relation, the new hole is cut by urging the dies toward each other in the same manner as specified in the normal operation of the tool.

The cutting action is illustrated in Fig. 12 wherein the aperture IS in the metal blank is larger than the minimum cross section of the conical faced cutting member 9, thereby permitting the conical face H to enter and center itself in thehole IS. The first application of pressure causes the bevelled knife edge of the female die 4- to penetrate into the blank, in the same manner as described for the operations: of the tool as shown in Fig. 1, until the resistance induced thereby is equal to the force required to shear the slug 8 from the blank. In the meantime, the cutting member 9 has been bending the slug portion 8 of the blank to conform to the contour of the conical face H of the member 9. Thereafter, continued application of pressure between the members 4 and S will cause the male member 9 to complete the severance of the slug by a shearing action similar to that shown and described in connection with Figs. and 11.

His obvious that different sized holes may be cut by using with the driving screw l, washer 3 and carrier 2 sets of complementary dies a and 9 of varying diameters together with a spacer 6 of correspondingly varied diameter.

Having thus described the principle and the operation of my tool, I wish to set forth several other embodiments and their advantages. Fig. 3 shows a modification similar to Fig. 1 except that the tubular die 4 and the washer 3 have been made integral with the carrier 2, of Fig. 1, forming one member I8, and since it is centrally disposed by the carrier, the spacer 6 is no longer needed. Since there is no removable part correponding to the inside diameter of the tubular die, it is necessary to provide opportunity for removing the cut-out portion 8 of the material which might become lodged in the recess l9. Therefore, I have provided keyways or slots 20, shown in Fig. 4, on opposite sides of the tapped bore in the base of the combined carrier-die l8, into which a suitable fiat instrument might be inserted and used as a punch in removing the cutout portion.

Likewise, the head of the driving screw l3 and the cutting member 9, as shown in Figs. 1 and 2, may be combined to form one integral piece similar to the part 2| shown in Fig. 5. This combination of driving screw head and cutting die into one integral part is preferably not used with the integral tubular die, washer, and carrier [8, as shown in Fig. 3, since there would then be no spacing member 6 to provide a surface for the rotation of the driving screw head other than the metal blank of the material itself. An advantage of these embodiments occurs where a single sized hole is constantly being made. Then, one of these combinations, resulting in the reduction of the number of parts, would be preferred to the multi-part tool as shown in Figs. 1 and 2.

Fig. 5 illustrates an embodiment of my invention similar to that shown in Fig. 1 except that the cutting member 9 and fixed head l3 of the driving screw I have been replaced by one integral part 2| with a portion 24 in this arrangement corresponding to the arrangement of the cutting member 9 in Fig. 1, but made larger than the diameter of the tubular die 5. Therefore, the principle of operation of this embodiment varies from that of the embodiment of Fig. 1 in that the enlarged hole is cut by forcing the tubular die 4 completely through the blank I! and against the base, or portion 24. It is to be understood that the hole cut in this instance will not have a cylindrical wall, but will be forced into a conical surface because of the conical shape of the cutting edge of the tubular die 4, as shown at 25. It will thus be observed that the use of this embodiment will be limited to occasions where the interior shape of the hole is of no moment, or where such countersink shape is desired, and also it is to be observed that the use of this embodiment of the invention, since it requires greater force to drive the tubular die 4 through the metal than in the embodiments where a cutting member is used in cooperation with the tubular die 4, will be limited to soft metals such as aluminum, zinc, etc., or relatively thin blanks.

Another variation in my invention is shown in Figs. 6 and 7, wherein a cutting member to be used in lieu of the cutting member 9 is constructed with its cutting face composed of four helical surfaces of equal pitch, with the pitch path of the surfaces in successively reversed arrangement. The lines 22 are the most external points on the cutting face of said die, and the lines 23 constitute the points of greatest recession on the face of said die. The advantage of a cutting member of this structure is that in the cutting of harder blanks or blanks of more than ordinary thickness, when the pitch of the helix is equal to or greater than the thickness of the blank tobe cut, the force is not applied on the entire surface at one time, but only at the two points 22 at the beginning of the operation, and at no more than four points at any time thereafter until the completion of the operation when the force is applied again through the two points 23. The effect of this application of force is somewhat similar to the effect of cutting with a pair of scissors, in that, in principle, the cutting is intermediate means for aligning said dies including a driving 7 complished at only one point along a line ata .time.

This same principle may be accomplished by using the normal cutting member 9, but varying the plane of the cutting edge of the normal tubular die 4, to a shape as shown in Fig. 8, wherein the bevelled surface constituting the cutting edge 26 is formed as by the intersection, with a cylinder, generated by two diametrically opposed elements of a right cone concentric with the cylinder, while the axis of the cylinder is progressively moved ain'ally in one direction through ninety degrees of rotation of the conical elements and then, the axial progressive movement is reversed through the next ninety degrees of rotation.

It is to be observed that there is no advantage to be obtained by using a cutting member, as shown in the embodiment illustrated by Figs. 6 and '7, in combination with a tubular die, as illustrated in Fig. 8, the use of one or the other of said embodiments accomplishing the desired purpose.

It is believed that the many advantages of a hole enlarging tool constructed in accordance with the present invention will be readily understood, and although preferred embodiments of the invention are as illustrated and described, it is to be understood that further modifications and changes in the details of construction may be resorted to which will fall within the scope of the invention as' claimed.

What is claimed is:

1. A hand tool for cutting holes in sheet material, comprising, a male die, a female die, said dies having cooperating cutting edges and being adapted to receive a blank of said sheet material therebetween, said female die having an annular bevelled cutting edge with the surface of the bevel converging toward and intersecting with the inner surface of the die, said bevel being of such pitch that it has less resistance than the male member to relative motion for a predetermined depth of cut, but has a greater resistance than the male member beyond said depth of out to thereby provide a severance of the material of the plane surfaces thereof,

screw, and means cooperating with said driving screw for moving said dies relatively towards each other.

2. A hand tool for forming holes in sheet material comprising a cutting member, a female die, said die and said cutting member having cooperating cutting edges and aligned bores therein and being adapted to receive a blank of said sheet material therebetween, said female die having an annular bevelled cutting edge with the surface of the bevel converging toward and intersecting with the inner surface of the die, said bevel being of such pitch that it has less resistance than the male member to relative motion for a predetermined depth of cut, but has a greater resistance than the male member beyond said depth of cut to thereby provide a severance of the material intermediate of the plane surfaces thereof, a driving screw with head and shanks, said shank being adapted to extend through the blank and to engage in the bores for guiding the cutting member, and a threaded carrier drivingly connected with said driving screw-. to urge said tubular die and said cutting member towards each other for cutting the blank.

3. A hand tool for forming holes in sheet material comprising, a male die and'a female die having cooperating cutting edges, said female die having an annular bevelled cutting edge disposed at the inner periphery of the die, said bevel being of such pitch that it will penetrate sufficiently to locate the burr formed by the severing action of the dies intermediate of the SUI-(.20 faces of the blank and provide a resistance when substantially at said burr position that is greater than the shearing strength of the material, means for aligning said dies, and means for urging them relatively, towards each other, to cause; 5 said knife edge to become imbedded in thematerial to be cut and to thereafter shear the material delimited by the said knife edge. 1

4. A hand tool for forming holes in sheet'material comprising, a male die, a female die, said dies having cooperating cutting edges and concentric bores therein, said female die having an annular bevelled cutting edge with the surface of the bevel converging toward and intersecting with the inner surface of the die, said bevel be- 5135 ing of such pitch that it has less resistance than the male member to relative motion for a predetermineddepth of cut, but has a greater resistance than the male member beyond said depth of cut to thereby provide a severance of L40 the material intermediate of the plane surfaces thereof, one of said dies having its cutting edge projecting from a plane normal to the axis of said die, aligning means adapted to extend through said bores and the blank to be cut by said dies, and screw means for urging said dies towards each other, thereby cutting said blank.

5. A hand tool comprising, a male and female member adapted to receive a sheet of material therebetween, said male member being formed 0 with a convex conical surface for centering said cutting members with respect to an opening in said material, said dies having cooperating cutting edges and concentric bores therein, aligning means adapted to extend through said dies 5 and opening for aligning the same, and screw means for urging said dies towards each other, thereby cutting said sheet material.

'WILL-IAM o. REESER.

CERI'IFI'CA'I'E OF CORRECTION. ratent No. 2,176, 9L5 October 2h, 1959.

WILLIAM O. REESER. I

. It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 51, strike out the words "thereof to receive the slug 8 to he cut from the" and insert the same after "portion" in line 29; and that the said Letters Patent should be readwith this correction therein, that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of January, A. D; l9h0.

Henry Van Arsdale,

( eal) Acting Commissioner of Patents.- 

